The invention relates to a battery cable clamp for vehicles, with a mounting device for a cable end piece in which two clamp parts are held together in electrically conducting contact via a pressed connection that can be released by an auxiliary drive with a high separating force, as well as a method for manufacturing such a cable clamp.
A cable clamp of this kind and a method for its manufacture are known from WO 95/21454 A the U.S. equivalent of which is U.S. Pat. No. 5,725,399. The two clamp parts have a cylindrical surface. This produces various disadvantages. First, the contact force depends on the manufacturing tolerances of the two clamp parts and cannot be exactly defined. From this there arises the disadvantage that the auxiliary drive must be dimensioned so that sufficient efficacy is obtained under extreme conditions. Since the auxiliary drive as a rule is provided by an explosive capsule, the result is a relatively high brisance of the explosive capsule. As a result, a reliable prevention of an inadvertent triggering of the explosive capsule which would endanger the health of a person (for example, during a repair in the engine compartment) is required. There is also considerable expense associated with a protective sheath, for example, as well as a relatively large additional weight associated therewith for the entire cable clamp.
The efficacy of a cable clamp with cylindrical contact surfaces on the clamp parts poses problems, since the two clamp parts do not separate until a considerable distance has been traveled. If an explosive charge is used as an auxiliary drive as explained above, its effect is determined by the amount of gas that is produced when the explosive capsule is triggered. A gas volume that is proportional to the distance is used to separate the two clamp parts from one another. Since the gas volume must both exert the breakaway forces for the clamp connection and produce the relative movement of the two clamp parts away from one another, a considerable amount of explosive is needed. This presents the considerable disadvantages previously described.
The object of the present invention is to provide a battery cable clamp of in which the two clamp parts are separated from one another in a definite fashion, with a minimum expulsion force of the auxiliary drive and to provide a method by which these effects can be achieved at a low manufacturing cost.
This and other objects and advantages are achieved by the battery cable clamp according to the present invention, in which the use of a cone (conical seat), because of the self-locking effect of a cone, results in a specific retaining force of the two clamp parts and results in contact separation with a minimum relative movement between the two clamp parts. This is true provided that contact with the wall is avoided. A conical seat in turn is easy to manufacture, since any manufacturing tolerances due to the surface structure are largely compensated. In addition, the clamping force can be simply monitored throughout the entire assembly process, and thus the breakaway force can be set in a specific ratio to the maximum clamping force.
As a rule, the breakaway force is generated with the aid of an explosive. The quantity of explosive can be relatively small since it is merely necessary to overcome the breakaway force. Because of the resultant relative movement, the contact separation is guaranteed to be rapid and safe.
Optimum control of the contact force and breakaway force can be achieved by a number of different measures. Thus the two cone angles can be made nearly identical. In contrast to a relative difference between the two cone angles, this produces a contact surface on the two clamp parts over their entire surfaces that are in contact with each other. The contact surfaces can be additionally surface-treated, plated by tinning and/or glued together, for example. The adhesive can be made so that it becomes effective only during the fitting process. The adhesive force can also depend on the squeezing pressure. This produces a clamping connection of the two clamp parts that is stable in the long term and remains practically constant over the entire lifetime in terms of expulsion force.
In order to avoid reactions between the auxiliary drive and the battery terminal, the recoil force at the battery terminal can be deflected. This deflection can be at a sharp angle to the departure direction of the cable clamp, for example. In addition, the clamp parts can be provided with an insulating protective sheath. This serves in particular for electrical insulation. It can also serve to hold the two clamp parts a specific distance apart after their separation. For this purpose, the sheath can be opened in the direction of movement of one clamp part. In addition, it can have latching means for the clamp part that is removed from the other clamp part. As a result of these latching means, the movement of the clamp part is limited and the two clamp parts are prevented from subsequently approaching one another again and restoring contact between them.
The invention will now be described in greater detail with reference to the drawings.